Horizontal sliding windows have been well accepted in the residential, commercial and mobile home fields for a number of years. They have been favored architecturally, tending to give a long low line to the structure. They do not require complex mechanism for opening and closing as in the case of gear operated casement windows or counter balanced double hung windows. The weight of the moving window or windows is supported totally by the structure and the user need only exert sufficient force to overcome the sliding friction to open or close the window.
Typically, horizontal sliding windows are fashioned generally as horizontal versions of a double hung window having a frame about each pane of glass and a stile portion. Each of these add to the weight and cost of the window and serve to reduce the overall available window space by placing an undesirable interfering mullion at the center of the window or multiple interfering mullions when the window is partially open.